This section provides background information related to the present disclosure which is not necessarily prior art.
Shock absorbers are used in conjunction with automotive suspension systems and other suspension systems to absorb unwanted vibrations which occur during movement of the suspension system. In order to absorb these unwanted vibrations, automotive shock absorbers are generally connected between the sprung (body) and the unsprung (suspension/chassis) masses of the automobile.
The most common type of shock absorbers for automobiles are the dashpot type in which a piston is located within a pressure tube and is connected to the sprung mass of the vehicle through a piston rod. The piston divides the pressure tube into an upper working chamber and a lower working chamber. Because the piston, through valving, has the ability to limit the flow of damping fluid between the upper and lower working chambers within the pressure tube when the shock absorber is compressed or extended, the shock absorber is able to produce a damping force which counteracts the vibrations which would otherwise be transmitted from the unsprung mass to the sprung mass. In a dual tube shock absorber, a fluid reservoir is defined between the pressure tube and a reserve tube which is positioned around the pressure tube. A base valve is located between the lower working chamber and the fluid reservoir to also produce a damping force which counteracts the vibration which would otherwise be transmitted from the unsprung portion to the sprung portion of the automobile during stroking of the shock absorber.
A conventional monotube shock absorber typically includes highly pressurized hydraulic fluid because its ability to dampen vibrations is limited by the initial static pressure of the hydraulic fluid. Having to maintain a high initial static pressure is undesirable for a number of reasons. A monotube shock absorber configured to operate at a lower pressure, thus reducing friction at the seals, would therefore be desirable. A monotube shock absorber that does not experience excessive noise caused by cavitation would also be desirable. Furthermore, methods and devices for securing a fixed valve assembly within a tube of a monotube shock absorber would be desirable.